Observation of a cross-section enhancement near the $t\bar{t}$ production threshold in $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

TL;DR

The ATLAS experiment observed an excess of top-antitop events near the production threshold at 13 TeV, suggesting possible formation of quasi-bound states, marking a significant experimental finding in top quark physics.

Contribution

First experimental observation of a threshold enhancement in top-antitop production consistent with quasi-bound state formation, confirming a hypothesis from nearly 40 years ago.

Findings

Observed a significant excess of $tar{t}$ events near threshold

Results are consistent with formation of $tar{t}$ quasi-bound states

Summarized experimental evidence and future research directions

Abstract

A significant excess of $t\bar{t}$ events near the production threshold was observed in LHC Run-2 data by the ATLAS Collaboration. It is consistent with the formation of $t\bar{t}$ quasi-bound states, which were first hypothesised almost 40 years ago. This contribution summarises the experimental results and outlines a path toward further characterisation of the excess.